The present invention relates to an arrangement for covering and sealing the open space between the driving and driven parts of a constant velocity universal joint. The arrangement includes a sealing boot, one end of which is fastened to the driven part of the joint. The other end of the sealing boot facing away from the universal joint is fastened to a sleeve which is axially displaceable and is arranged coaxially surrounding a drive shaft connected to the driving member.
In such an arrangement, the sealing boot extends over the open space in the universal joint extending between the driving part, such as an inner joint member, and the driven part, such as an outer joint member, so that there is relative movement between the sealing boot and the parts extending from the universal joint.
In a known arrangement for sealing a constant velocity universal joint, note German Pat. No. 24 30 109, a sealing boot is used in which the displacement of the universal joint is compensated by an axial deformation of the folds of the sealing boot. Sealing boots of this type contain in their interior a large amount of lubricant, which results in the disadvantage that the operation of universal joints equipped with such sealing boots is very expensive. Centrifugal forces acting on the lubricant during rotation of the joint are another problem resulting from this arrangement.
Another sealing arrangement for a constant velocity universal joint using a sealing boot is disclosed in German Pat. No. 22 05 798. In this arrangement, the sealing boot is secured to the driving and driven parts of the universal joint and is additionally fixed to a cage within the universal joint. By fixing the sealing boot to the cage, a division of the open space enclosed by the sealing boot is achieved, that is, there is an exact division of the bending angle and of the sliding path. Since the cage is positioned within the outer joint member, the intermediate fastening of the sealing boot to the cage results in two portions of the sealing boot which extend asymmetrically relative to one another and are subject to different loads and conditions during operation, so that in such an arrangement it would be obvious to form each sealing boot portion from a material having different properties. This sealing arrangement has the further disadvantage that the cage must not only serve to provide a control action in the universal joint, but must also serve to support the sealing boot.
In view of the foregoing, it is the primary object of the present invention to provide a sealing arrangement for constant velocity universal joints wherein the loads acting on the sealing boot are reduced by a separation of the bending angle and the sliding path.
It is another object of the invention, to afford a sealing arrangement for a universal joint which is inexpensive to operate, uses small quantities of lubricant and is composed of simple structural components.